More keen than we let on. The experiment suggested that infrasound can fill us with fear, anxiety, make us imagine pressure on our chest.

Similarly you have some species that will flee any sort of electromagnetic pulse, immediately registering it as a threat. Birds of my word migrate based on the direction of the poles. So it makes you wonder.

Maybe convergent evolution has given you guys some traits that keys you in on something that you can't consciously detect. The sense is there, but only there enough for you to be on guard or to know not to approach. I just have no clue what that something would be. [Unfortunately he's not excluding Narvin from that evolutionary line, because it's useful.]